The present invention relates to electronic circuit packages with dendrites connecting two conductive surfaces through a film and method for producing same. The dendrites electrically connect the two conductive surfaces and avoid the need for drilling or punching holes for vias or through-holes.
Electronic circuits contain many (sometimes millions) of components such as resistors, capacitors, inductors, diodes, electromechanical switches, and transistors. High density packaging of electronic components is particularly important to allow fast access to large amounts of data in computers. High density electronic circuit packages also are important in high frequency devices and communications devices. The components are connected to form circuits and circuits are connected to form functioning devices. The connections perform power and signal distribution. In a multi-layer electronic circuit package, some layers of the package serve as power planes and other layers serve as signal planes, depending on the operational requirements of the device. The devices require mechanical support and structural protection. The circuits themselves require electrical energy to function. The functioning devices, however, produce heat, or thermal energy which must be dissipated so that the. devices do not stop functioning. Moreover, while high density packaging of a number of components can improve performance of the device, the heat produced by the power-consuming components can be such that performance and reliability of the devices is adversely impacted. The adverse impact arises from electrical problems such as increased resistivity and mechanical problems such as thermal stress caused by increased heat.
Electronic circuit packages, such as chips, modules, circuit cards, circuit boards, and combinations of these, thus must meet a number of requirements for optimum performance. The package must be structurally sturdy enough to support and protect the components and the wiring. In addition, the package must be capable of dissipating heat and must have a coefficient of thermal expansion that is compatible with that of the components. Finally, to be commercially useful, the package should be inexpensive to produce and easy to manufacture.
High density packages necessarily involve increased wiring density and thinner dielectric coatings between layers in a multi-layer electronic circuit package. The layers in a multi-layer package typically are electrically connected by vias and through-holes. The termxe2x80x9cviaxe2x80x9d is used for a conductive pathway between adjacent layers in a multi-layer electronic circuit package. The termxe2x80x9cthrough-holexe2x80x9d is used for a conductive pathway that extends to a non-adjacent layer. For high density packages the through-holes are increasingly narrow in diameter and the through-holes in each layer must be aligned precisely. This invention provides an alternative means of interconnectionxe2x80x94namely electrical interconnection using dendrites. Dendrite interconnection. avoids the need to drill or punch holes for vias or through-holes.
An object of this invention is to provide a means for connecting two conductors along the vertical or z-axis without using vias or through-holes, but still resulting in tight tolerances and high yield. Dendrite interconnections accomplish this purpose.
It is an object of this invention to provide an electronic circuit package with dendrites forming electrical connections between a first conductive layer and second conductive layer.
A further object of this invention is to provide an electronic circuit package that provides electrical connection in the z-axis using dendrites, thereby eliminating the need for drilling or punching through-holes or vias in the manufacturing process of the electronic circuit package.
A third object of this invention is to provide a method of fabrication of electronic circuit packages with dendrites forming electrical connections between a first conductive layer and a second conductive layer.
Accordingly, a method is provided for connecting two conductive layers in an electronic circuit package comprising the steps of forming dendrites on selected regions of a first conductive layer, forming dendrites on selected regions of a second conductive layer, applying an epoxy dielectric material over the first conductive layer, and compressively attaching the second conductive layer to the first conductive layer such that the dendrites on the first conductive layer contact the dendrites on the second conductive layer. Also claimed is an electronic circuit package incorporating the dendrites used for electrical interconnection manufactured in accordance with the present invention. An alternative embodiment of the invention utilizes an intermediate surface metal with. dendrites in place of a xe2x80x9cthrough via.xe2x80x9d
It is an advantage of the present invention that the dendrites provide electrical connection between two conductive layers of the electronic circuit package.
It is a further advantage that the dendrites provide electrical connection in the z-axis using dendrites, thereby eliminating the need for photodefining, laser ablating, drilling or punching through-holes or vias in the manufacturing process of the electronic circuit package.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention taken in conjunction with the accompanying drawings and examples.